1. Field of the Invention
The present invention relates to an ethylene-.alpha.-olefin-nonconjugated polyene random copolymer, a composition comprising said copolymer and a process for producing said copolymer. More precisely, the present invention relates to an ethylene-.alpha.-olefin-nonconjugated polyene random copolymer having a wide molecular weight distribution and superior in processability, a composition comprising said copolymer and a process for producing said copolymer.
2. Description of Related Art
Because of their good performances such as good heat resistance, good weathering resistance, good ozone resistance and the like, ethylene-.alpha.-olefin-nonconjugated polyene random copolymers have used in wide application as automobile materials, building materials, industrial materials, cable materials and the like. The copolymers have conventionally been produced using vanadium catalysts.
The copolymers obtained by using these catalysts, however, had a narrow molecular weight distribution and are inferior in processability. As a means for improving these defects, for example, a process has been proposed in which a multi-step polymerization vessel is used to form a polymer having varied molecular weight and a different composition. Actually, however, a polymer having a desired molecular weight distribution and composition could not be easily obtained. In addition, the process had a problem that the productivity of the reaction vessel was very low due to the necessity of limiting the ratio of polymers produced in respective polymerization step-vessels.
Recently, on the other hand, numerous processes for producing ethylene-.alpha.-olefin-nonconjugated polyene random copolymers have been proposed using highly reactive metallocene catalysts. These processes, however, had also a defect that the polymer produced by these processes had a very narrow molecular weight distribution like the polymers obtained with the conventional vanadium catalysts and thus their processability was greatly problematic.
Under these circumstances, the purpose of the invention is to provide an ethylene-.alpha.-olefin-nonconjugated polyene random copolymer having a wide molecular weight distribution and superior inprocessability, a composition comprising said copolymer and a process for producing said copolymer.